title: Loss of sulfonamide resistance in Neisseria meningitidis.
abstract: Four strains of Neisseria meningitidis were studied during serial passage. From two strains which originally were sulfonamide resistant, variants developed that had altered susceptibility to sulfonamides. One of the variants became relatively highly sulfonamide-sensitive, the other exhibited merely reduced sulfonamide resistance. There was a difference in the resistance pattern for two sulfonamides (sulfaisodimidine and sulfamethoxazole), and the effect of inoculum size and growth conditions in three different media could be demonstrated. Although the patterns of susceptibility to other antibacterial agents were different for the strains studied, no further susceptibility alterations occurred in parallel to the sulfonamide sensitivity changes. The variants also lost their ability to liberate free endotoxin.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004352:Drug Resistance, Microbial; D009345:Neisseria meningitidis / Q000187:drug effects* / Q000254:growth & development; D013420:Sulfamethoxazole / Q000494:pharmacology*; D013443:Sulfisomidine / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D013420:Sulfamethoxazole; D013443:Sulfisomidine